Brain functions modulating redistribution of natural killer cells accompanying cognitive appraisal of acute stress

Abstract

Acute stress increases the number of natural killer (NK) cells, which plays a critical role in innate immunity, in peripheral circulation within several minutes. This phenomenon is called redistribution of NK cells and has been thought to reflect facilitation of preventive defense. Redistribution of NK cells is not a stereotyped response but is sensitive to cognitive appraisals of stressors, and thus might be under control by the brain. We have explored neural mechanisms of the top-down modulation of NK cell distribution by the brain using simultaneous measurement of brain activity by positron emission tomography and the number of NK cells in blood during cognitive acute stress tasks where stressor controllability and cognitive flexibility were manipulated. Results suggested that the dorsolateral prefrontal and orbitofrontal cortices might be involved in appraisals of stressors, and modulate NK cell redistribution via the anterior cingulate cortex and the vagus nerve.